Yes in certain parts of that shot you can see the plywood under the glass which is orange, but there is no plywood in the hull sides. This glue is caked on, 1/8" in some spots. I have used this wire cup brush on a die grinder with good results.
But it I need to remove all traces because I want to fill the weave of the hull sides with epoxy or fairing compound and paint. I am concerned the leftover glue will cause lifting in the future. Any opinions on the glue reacting with and epoxy/cabosil mixture?